Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include "bits/stdc++.h"
using namespace std;
typedef long long LL;
typedef pair<int, int> P;
char maze[50][51];
int dist[50][50];
int dx[] = { -1,0,1,0 };
int dy[] = { 0,1,0,-1 };
int main() {
	int H, W;
	cin >> H >> W;
	int cnt = 0;
	for (int i = 0; i < H; i++) {
		cin >> maze[i];
		for (int j = 0; j < W; j++) if (maze[i][j] == '.') cnt++;
	}
	queue<P> Q;
	Q.push(P(0, 0));
	memset(dist, -1, sizeof(dist));
	dist[0][0] = 1;
	while (!Q.empty()) {
		P p = Q.front(); Q.pop();
		if (p.first == H - 1 && p.second == W - 1) break;
		for (int i = 0; i < 4; i++) {
			int nx = p.second + dx[i], ny = p.first + dy[i];
			if (0 > nx || nx >= W || 0 > ny || ny >= H || maze[ny][nx] == '#') continue;
			if (dist[ny][nx] == -1) {
				dist[ny][nx] = dist[p.first][p.second] + 1;
				Q.push(P(ny, nx));
			}
		}
	}
	if (dist[H - 1][W - 1] == -1) {
		cout << -1 << endl;
	}
	else {
		cout << cnt - dist[H - 1][W - 1] << endl;
	}
}